• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 추계학술대회 논문집 학회본부
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• pp.462-466
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• 1989

This paper describes the methods of spline low-order polynomial trajectory planning using only a few limited look-ahead knots on the desired trajectory for the real-time computing. Specifically presented are the mixed joint trajectory planning methods which apply linear or LSPB method to initial and finial segments, overlapped cubic spline method to the other segments, where the displacements for initial and finial segments are chosen to be relatively smaller than the displacements for the other, equidistant segments. Experimental and simulation results of these methods show smooth motions and improved path tracking performances compared with any other interpolated joint trajectory planning methods.

• 제어로봇시스템학회논문지
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• 제8권10호
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• pp.890-897
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• 2002

This paper deals with the reduction of trajectory tracking error by changing the initial postures of a biped robot. Gait of a biped robot depends on the constraints of mechanical kinematics and the initial states including the posture. Also the dynamic walking stability in a biped robot system is analyzed by zero moment point(ZMP) among the stabilization indices. Path trajectory, in which knee joint is bent forward like human's cases, is applied to most cases considered with above conditions. A new initial posture, which is similar to bird's gait, is proposed to decrease trajectory tracking error and it is verified through real experimental results.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 26-27 Oct. 1990
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• pp.135-139
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• 1990

In general, the control of robot arms falls into two board categories (position control and force control). The joint interpolated trajectory schemes generally interpolate the desired joint path by a class of polynomial functions and generate a sequence of time based control set points for the control of a manipulator from a initial location to its destination. A digital position controller was designed and adapted to the industrial balancing manipulator. And also, the joint interpolated trajectory using 3rd order polynomial was generated in this study. The IBM PC used as the main controller and the trajectory planner had enough run-time capabilities. The 8097BH microcontroller is an integral pan of the joint controller which directly controls an axis of motion. The PI servo control system to treat each joint of the robot arm as a independent joint servo mechanism had satisfying performance, and a sequence of time-based intermediate configurations of the manipulator hand showed good continuity and smoothness on position and velocity of the manipulator's joint coordinates along the trajectory.

• 산업공학
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• 제3권2호
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• pp.23-38
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• 1990

The use of robots for painting operations is a powerful alternative as a means for automation and quality improvement. A typical method being used for motion planning of the painting robot is to guide the robot along the desired path : the "lead-through" method. Although this method is simple and has been widely used, it has several drawbacks a) The robot cannot be used during the teaching period, b) A human is exposed to a hostile environment, c) The motions taught are, at best, human's skill level. To deal with the above problems, an integrated robot-trajectory planning scheme is presented. The new scheme takes CAD data describing the shape and geometry of the objects, and outputs an optimal trajectory in the sense of coating thickness and painting time. The purpose of this paper is to investigate theoretical backgrounds for such a scheme including geometric modeling, painting mechanics and robot trajectory planning, and develop algorithms for generating spray gun paths and minimum-time robot trajectories. Future study is to implement these algorithms on an workstation to develop an integrated software system ; ATPS(Automatic Trajectory Planning System) for spray painting robots.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.30.6-30
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• 2001

We build near minimum-time trajectory planning algorithm for Wheeled mobile robots (WMRs) With Piece-Wise Constant control voltages satisfying i) initial and final postures and velocities as well as ii) voltage constraints We consider trajectory planning problem for cornering motion with a path-deviation requirement for obstacle avoidance. We divide our trajectory planning algorithm for cornering motion into five ordered sections: translational, transient, rotational, transient, and translational sections. Transforming dynamics into uncorrelated form with respect to translational and rotational velocities, we can make controls for translation/rotational velocities to be independent. By planning each section with constant voltages, and integrating five sections with adjustment of numbers of steps, the overall trajectory is planned. The performance is very close to the minimum-time solution, which is validated via simulation studies.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.627-634
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• 1989

A collision-free trajectory planning algorithm using the iterative learning concept is proposed for dual robot arms in a 3-D workspace to accurately follow their specified paths with constant velocities. Specifically, a collision-free trajectory minimizing the trajectory error is obtained first by employing the linear programming technique. Then the total operating time is iteratively adjusted based on the maximum trajectory error of the previous iteration so that the collision-free trajectory has no deviation from the specified path and also the operating time is near-minimal.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.168-173
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• 2003

In this paper, we will present a deeper look on optimal design methods that are related to path-planning for a mobile robot. To control the motion of a mobile robot in a clustered environment, it's necessary to know a suitable trajectory assuming certain start and goal point. Up to now, there are many literatures that concern optimal path planning for an obstacle avoided mobile robot. Among those literatures, we have chosen 2 novel methods for our further analysis. The first approach [4] is based on HJB(Hamilton-Jacobi-Bellman) equation whose solution is the return-function that helps to generate a shortest path to the goal. The later [5] is called polynomial-path-planning approach, in this method, a shortest polynomial-shape path would become a solution if it was a collision-free path. The camera network plays the role as sensors to generate updated map which locates the static and dynamic objects in the space. Therefore, the exhibition of both path planning and dynamic obstacle avoidance by the updated map would be accomplished simultaneously. As we mentioned before, our research will include the motion control of a true mobile robot on those optimal planned paths which were generated by above algorithms. Base on the kinematic and dynamic simulation results, we can realize the affection of moving speed to the stable of motion on each generated path. Also, we can verify the time-optimal trajectory through velocity tuning. To simplify for our analysis, we assumed the obstacles are cylindrical circular objects with the same size.

• 로봇학회논문지
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• 제7권2호
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• pp.150-159
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• 2012

In this paper, we propose a cost-aware Rapidly-exploring Random Tree (RRT) path planning algorithm for mobile robots. A mobile robot is presented with a cost map of the field of interest and assigned to move from one location to another. As a robot moves, the robot is penalized by the cost at its current location according to the cost map. The overall cost of the robot is determined by the trajectory of the robot. The goal of the proposed cost-aware RRT algorithm is to find a trajectory with the minimal cost. The cost map of the field can represent environmental parameters, such as temperature, humidity, chemical concentration, wireless signal strength, and stealthiness. For example, if the cost map represents packet drop rates at different locations, the minimum cost path between two locations is the path with the best possible communication, which is desirable when a robot operates under the environment with weak wireless signals. The proposed cost-aware RRT algorithm extends the basic RRT algorithm by considering the cost map when extending a motion segment. We show that the proposed algorithm gives an outstanding performance compared to the basic RRT method. We also demonstrate that the use of rejection sampling can give better results through extensive simulation.

• 한국정밀공학회지
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• 제15권1호
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• pp.78-86
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• 1998

This paper presents a numerical method of the minimum-time trajectory planning for a robot manipulator amid obstacles. Each joint displacement is represented by the linear combination of the finite-term quintic B-splines which are the known functions of the path parameter. The time is represented by the linear function of the same path parameter. Since the geometric path is not fixed and the time is linear to the path parameter, the coefficients of the splines and the time-scale factor span a finite-dimensional vector space, a point in which uniquely represents the manipulator motion. The displacement, the velocity and the acceleration conditions at the starting and the goal positions are transformed into the linear equality constraints on the coefficients of the splines, which reduce the dimension of the vector space. The optimization is performed in the reduced vector space using nonlinear programming. The total moving time is the main performance index which should be minimized. The constraints on the actuator forces and that of the obstacle-avoidance, together with sufficiently large weighting coefficients, are included in the augmented performance index. In the numerical implementation, the minimum-time motion is obtained for a planar 3-1ink manipulator amid several rectangular obstacles without simplifying any dynamic or geometric models.

• 한국HCI학회논문지
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• 제5권2호
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• pp.15-24
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• 2010

디지로그 북(Digilog book)은 기존 서적과 디지털 콘텐츠을 융합함으로써, 아날로그적 감성과 디지털 오감을 함께 제공하는 증강현실기반 차세대 출판물이다. 디지로그 북을 저작할 수 있는 저작 소프트웨어인 아틀렛(ARtalet)은 증강현실 환경에서 3 차원 사용자 인터페이스를 이용한 직관적인 In-Situ 저작 환경을 제공한다. 본 논문은 디지로그 북에 증강된 3D 객체에 이동 경로를 생성하고 조작 할 수 있는, 아틀렛 저작 환경 기반의 이동 궤적 편집 기법을 제안한다. 구체적으로 이동 궤적의 조정점(Control point)을 적절히 할당하기 위해서 3차원 조작도구의 이동 좌표에 대하여 조정점 할당 검사를 한다. 그리고 부드러운 곡선 형태로 이동 궤적을 복원하기 위해서 스플라인을 이용한 보간 과정을 수행한다. 또한 작고 밀집된 이동 궤적의 조정점을 효과적으로 선택하기 위해서 동적 스코어(Score)를 기반으로 한 조정점 선택 방법을 적용한다. 실험 결과 제안한 방법은 기존 방법에 비해 오차와 완료시간은 유의한 차이가 없었지만, 조정점의 수를 약 90% 이상 감소시킬 수 있었다. 이것은 매우 적은 수의 조정점만으로도 이동궤적을 복원할 수 있으며 추후 이동 궤적 조작에 필요한 조정점의 조작 횟수를 대폭 줄일 수 있다는 것을 의미한다. 또한 제안한 방법은 기존의 조정점 조작 방법에 비해 상대적으로 적은 손과 팔의 움직임만으로도 빠르게 이동 궤적의 형태를 변경 할 수 있었다. 본 논문에서 제안한 3D 객체의 이동 궤적 편집 방법은 몰입형 In-Situ 증강현실 환경의 교육, 게임, 디자인, 애니메이션, 시뮬레이션 등의 분야에서 드로잉 또는 곡선 편집 방법으로 응용될 수 있다.